This invention is a process for preventing the fatigue artifact in x-ray images in the form of white spots on positive images or dark spots on negative images produced through the use of xerographic selenium plates, and more specifically is a change in the development process used in xeroradiographic x-ray imaging wherein the selenium x-ray photoreceptor is pre-charged positively for a period of thirty seconds or more before the standard charging step.
The xerographic process can be used to produce x-ray images by charging a xerographic plate, and then selectively discharging the plate with an x-ray beam that has passed through the body tissue under examination. The prior art includes two commonly assigned U.S. Pat. Nos. 4,583,489and 4,624,544 which describe two x-ray systems of the type in which this invention could to be used, and are included herein by reference. In a typical xerographic system, for example, after the image is transferred to the paper, the plate is cleaned, heated for a period of time in a relaxer assembly and then stored until the next use. When the plate is needed it is passed over a charging scorotron before being exposed to the x-rays.
A problem is that for some plates, repeating artifacts in the form of spots appear on the image for the second and subsequent images. It has been found that if the plate is relaxed at an elevated temperature, 21/2 minutes at 130 degrees F. would be typical, and then stored in an uncharged condition for two or three hours, the next xerographic cycle will result in an image without artifacts. However, in order to maintain a minimum number of plates in the system, and to produce images at a commercial rate, it is not feasible to store each plate for a sufficient period after each use.